This invention relates in general to breathing apparatus and in particular to a new and useful protective breathing apparatus which comprises a breathing gas supply tube which is connected into a face mask which terminates in the interior of the face mask in a mouthpiece which is engageable with the person's mouth.
Full face masks are the conventional breathing connections. However, the strapping of such mask requires some practice to ensure the correct fit. Further known are half face masks. Since they require a particular contour of the sealing rim, they are very difficult to design and also to put on. They may best be connected for breathing through a mouthpiece. For this purpose, however, it is necessary to close the nose.
A prior art mouthpiece for breathing apparatus comprises an oxygen supply tube having an elliptic cross-section and a mouthpiece sleeve preferably of rubber, is engaged over the tube. The mouthpiece sleeve is formed with two flanges of which, during use, the inner one applies to the backside of the user's front teeth, while the outer one remains in front of the user's lips. Two resilient holders are secured to the mouthpiece sleeve in front of the outer flange, each carrying a plug on its end. During the use of the mouthpiece, these plugs close the nostrils. Since the shape of the user's faces vary, no safe seal can be obtained and noxious substances may penetrate from the ambience directly into the nose and the respiratory ducts. Also the nose plugs are very inconvenient for the user. (German Pat. No. 6669841).
Another prior art mouthpiece for protective breathing apparatus comprises a nose clamp which is displaceable. In addition to parts which can be introduced into the mouth, the mouthpiece carries a mouth flange covering the entire mouth region from the outside and bearing against the head strapping. Outside the mouth flange, the mouthpiece is provided with perpendicular, parallel guide surfaces. A U-shaped holding band is passed from above through two guide holes in such a manner that its ends apply against the guide surfaces and are clamped in the adjusted position. A nose clamping spring is pivotally mounted on the back of the holding band through a double lug, and the holding band is adjustable vertically. On its end, the nose clamping spring carries rubber discs. Due to the clamping, the nose clamp remains in the selected position of use, also when not in use so that the repeated use is facilitated. However, the attachment of the nose clamp requires additional handling and the time needed therefor is frequently not available in emergency cases. Moreover, during an extended use, the pressure of the nose clamp on the nose is inconvenient (German Pat. No. 10708055).